Abstract
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Objectives: To clarify the safety and efficacy of radioactive Iodine-125 seeds implantation (RISI) in the treatment of thoracic malignant tumors, and to explore the relationship between different doses of RISI and efficacy and side effects. Materials and Methods: Inclusion criteria: (1) Primary or metastatic tumors of the chest with definite pathological diagnosis; (2) unable or unsuitable for surgery or radiotherapy; (3) tumor diameter < 7cm, with appropriate puncture path; (4) no bleeding tendency; (5) KPS > 70 score. All patients underwent preoperative planning design, 3D printing template design and printing, CT-guided seeds implantation assisted by template and post-operative dosimetric verification. The patients were followed up regularly after treatment. The main outcome measures were local control rate and toxicity, and the secondary end-point was total survival. Short-term efficacy was evaluated based on RECIST criteria, and toxicity was evaluated based on CTCAE criteria. Statistical methods: Chi-square test was used to compare the rates. Kaplan-Meier method was used to analyze the local control rate and survival rate of patients. Log-rank test was used for univariate analysis and COX regression model was used for multivariate analysis.
Results: 41 cases of primary lung cancer and 51 cases of lung metastasis were included in the study. The median diameter of the lesion was 5 cm (1.4-7.0 cm). The median D90 was 142.6 Gy (81-241.8 Gy) obtained by post-operative dosimetric verification. The median follow-up period was 10.7 months (1-36.6 months). The 1-year and 3-year overall survival rate was 59.7% and 22.2%, respectively. The 1-year and 3-year local control rate was 64.9% and 32.8% respectively. Univariate analysis showed that target dose and type of lesion were correlated with local control. The 3-year local control rates for patients with D90 less than 140 Gy and those with D90 more than 140 Gy was 23.1% and 54.3%, respectively (p=0.014) (Figure 1). The 3-year local control rates of lung metastases was 43.9% which was superior to those of primary lung cancer’s 19.5% (2 years) (p=0.020) (Figure2). However, there was no significant difference in local control between patients who had received radiotherapy or not, different lesion volume and squamous cell carcinoma/adenocarcinoma (p > 0.05). Multivariate analysis showed that dose and type of lesion were independent factors may influence the local control (p < 0.05). No factors related to survival were found. In terms of side effects, the incidence of pneumothorax was 35.8% (34/92), and 6 patients needed surgical intervention for closed drainage (6.5%). The incidence of hemoptysis was 3.2%. The incidence of radiation toxicities were low: the incidence of ≥Grade 2 radiation pneumonia and esophagitis was 3.2% and 2.1%, respectively. 1 case of tracheal fistula (1.1%) and 2 cases of esophageal fistula (2.1%) were occurred.
Conclusions: RISI is safe and effective in the treatment of thoracic tumors. The common side effects of external irradiation, such as radiation pneumonia, esophagitis, skin reaction, etc., are low. Dose above 140 Gy can achieve a better local control.